1. Technical Field
The present invention relates to a projector.
2. Related Art
A method has been known in which two projectors are used to project and overlay the same images on one screen (projection surface) (see JP-A-5-107639, for example). According to such a method, the brightness of the projected, overlaid image light is nearly doubled, and hence the image light projected onto the screen is very bright.
In such overlay projection, however, it is not easy to accurately superimpose the image light from the two projectors on the screen. Inaccurate superimposition of the image light from the two projectors degrades the image quality of the projected image.
As a projector of related art capable of solving such a problem, a projector has been proposed which includes a polarization separation system that separates the light from an illuminator into a light beam containing a first polarization component and a light beam containing a second polarization component and directs them toward two image formation units, and a polarization combining system that combines the image light beams from the two image formation units (see JP-A-1-126678, for example).
According to the projector of related art, the light from the illuminator is separated into the light beam having the first polarization component and the light beam having the second polarization component, and the image formation units form the image light beams. Then, the polarization combining system combines the two image light beams, and a projection system projects the combined light beam onto a screen. Therefore, the image light beams from the two image formation units can be accurately superimposed on the screen. As a result, it is possible to prevent degradation in image quality of the projected image.
However, an investigation conducted by the inventor has shown that even when a light homogenizing system, such as a lens integrator, is used to make the in-plane light intensity distribution of the light emitted from the illuminator uniform in the projector of related art, the image light projected onto the screen presents color shading in the right-left direction (horizontal direction). When the image light projected onto the screen presents color shading in the right-left direction (horizontal direction), the image quality of the projected image is degraded.